發(fā)布時間：2018-10-11 11:53

【摘要】：KDP晶體(KH2PO4)是慣性約束核聚變固體激光器光路系統(tǒng)中的關鍵光學元件,制造精度要求很高,但是KDP晶體具有易潮解、質軟、脆性高、易開裂等不利于加工的特點,使其成為最難加工的光學元件。目前對KDP晶體的加工廣泛使用的是超精密飛切加工技術。如何在加工中控制好KDP晶體的粗糙度和波紋度誤差是當下研究的重點。本文首先分析了超精密飛切加工表面形貌形成過程仿真模型中需要考慮的影響因素,主要包括主軸的偏擺運動、刀具—工件的相對振動、切削過程刀具的熱變形情況和切削參數。該加工表面形貌形成過程仿真模型的建立是基于加工的運動規(guī)律,加工表面形貌由刀具在工件上的切削運動輪廓形成。因此分別對各影響因素建立了刀尖的運動規(guī)律。其中,由于切削過程中刀具熱膨脹導致的刀尖位移變化不能通過實驗測量。因此本文進行了超精密飛切加工主切削力的測量實驗,并建立了切削熱理論模型,計算了切削過程中不同切削參數和主切削力對應的輸入刀尖的熱流量,通過有限元仿真的方法分析了刀具熱變形所引起的刀尖位移變化,從而擬合得到了相應的刀尖位移方程。此外,本文還考慮了多次切削的切削截面輪廓干涉現象和刀尖圓弧半徑對于仿真中切削深度的影響,在仿真算法中進行了相應的設計并建立了完整的超精密飛切加工表面形貌的仿真模型。利用所建立的KDP晶體超精密飛切加工表面形貌的仿真模型,本文分別分析了切削參數、主軸偏擺運動、刀具—工件的相對振動以及刀具的熱變形對KDP晶體加工表面形貌的影響。分析過程中通過編程實現了對仿真形貌的濾波,形貌信息提取及粗糙度、波紋度誤差的評價。結果表明切削參數對工件表面粗糙度的影響較大,而主軸偏擺運動及刀具—工件相對振動情況對粗糙度和波紋度均有影響,刀具的熱變形不會對粗糙度和波紋度誤差造成明顯影響,其主要影響加工表面的面形特征。最后,進行了KDP晶體的超精密飛切加工實驗,對實驗結果進行了分析并驗證了超精密飛切加工表面形貌形成過程仿真模型的有效性及合理性。利用本文中的KDP晶體超精密飛切加工表面形貌形成過程仿真模型可以分析不同加工條件下的加工表面形貌變化規(guī)律,優(yōu)化加工過程參數,對于KDP晶體加工表面形貌精度的提高是很有意義的。
[Abstract]:KDP crystal (KH2PO4) is a key optical element in the optical system of inertial confinement fusion solid-state laser. The manufacturing precision is very high, but the KDP crystal has the characteristics of easy moisture solution, soft quality, high brittleness, easy cracking and so on. Make it the most difficult optical element to process. At present, ultra-precision flying cutting technology is widely used in the processing of KDP crystals. How to control the roughness and corrugation error of KDP crystal is the focus of current research. In this paper, the factors that need to be considered in the simulation model of the formation process of surface morphology in ultra-precision flying cutting are analyzed, including the deflection of the spindle, the relative vibration of the cutting tool and workpiece. Hot deformation of cutting tool and cutting parameters. The simulation model of the formation process of the machined surface topography is based on the motion law of the machining, and the machined surface morphology is formed by the cutting contour of the cutting tool on the workpiece. Therefore, the movement law of knife tip is established for each influencing factor. The change of tip displacement caused by cutting tool thermal expansion can not be measured experimentally. In this paper, the measurement experiment of the main cutting force of ultra-precision flying cutting is carried out, and the theoretical model of cutting heat is established, and the heat flux of the input cutter tip corresponding to different cutting parameters and main cutting forces in the cutting process is calculated. The change of tip displacement caused by tool thermal deformation is analyzed by finite element simulation method, and the corresponding tip displacement equation is obtained by fitting. In addition, the influence of the interference phenomenon of cutting cross-section profile and the radius of cutter tip arc on the cutting depth in the simulation is also considered in this paper. The simulation algorithm is designed and a complete simulation model of the surface morphology of ultra-precision flying cutting is established. Based on the simulation model of the surface morphology of ultra-precision flying cutting of KDP crystal, the effects of cutting parameters, the movement of spindle deflection, the relative vibration of cutter and workpiece and the thermal deformation of tool on the surface morphology of KDP crystal are analyzed in this paper. In the process of analysis, the filter of simulation topography, the extraction of topography information and the evaluation of roughness and corrugation error are realized by programming. The results show that the cutting parameters have a great influence on the surface roughness of the workpiece, while the movement of the spindle deflection and the relative vibration of the cutting tool and workpiece have effects on the roughness and the corrugation of the workpiece. The thermal deformation of the tool has no obvious effect on roughness and corrugation error, and it mainly affects the surface shape characteristics of the machined surface. Finally, the experiment of ultra-precision flying cutting of KDP crystal is carried out. The experimental results are analyzed and the validity and rationality of the simulation model for the formation process of surface morphology of ultra-precision flying cutting are verified. The simulation model of the formation process of the surface morphology in ultra-precision flight cutting of KDP crystal in this paper can be used to analyze the changing law of the surface morphology under different processing conditions and to optimize the processing process parameters. It is significant to improve the surface morphology precision of KDP crystal.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TL632;TN248.1

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本文編號：2264090